Currently, there are many known ways to treat long bone fractures. Common fracture treatments include: (1) non-surgical immobilization; (2) osteosuture and tension band technologies; (3) percutaneous fixation (e.g., using pins, wires, screws etc.); (4) rigid intramedullary nailing (e.g., using a large rod and external screws); (5) flexible plate osteosynthesis (e.g., a “load sharing” suture); (6) arthroplasty (e.g., using a prosthesis); (7) plating and other indication-specific techniques. Severe fractures that meet certain clinical criteria may require surgical repair rather than non-surgical immobilization.
The midshaft of an elongated or long bone is typically classified as the diaphysis. The end of such a bone is typically classified as the epiphysis. Bone that is transitional between the midshaft and the end is typically classified as the metaphysis.
Metaphysis and epiphysis bone are typically less dense, more cancellous (porous), and less cortical than diaphysis bone. Repair of metaphysis and epiphysis fractures are often complicated by their proximity to a joint. Because of such bone quality and anatomical differences, fixation of plates and screws in metaphysis and epiphysis bone is typically more difficult than fixation of plates and screws in diaphysis bone. This may be especially true if the patient is elderly and suffers from osteoporosis.
In general, fracture fixation may provide longitudinal (along the long axis of the bone), transverse (across the long axis of the bone), and rotational (about the long axis of the bone) stability. Fracture fixation may also preserve normal biologic and healing function.
There are two primary categories for surgical fixation: (1) a device that is within the skin (internal fixation); and (2) a device that extends out of the skin (external fixation). There are two common types of internal fixation approaches for long bone surgery (a) a plate that is screwed to the outside of the bone; or (b) a rod that goes down the center of the bone.
Plates and screws are characterized by relatively invasive surgery, support of fractured bone segments from one side outside of bone, and screws that anchor into the plate and through the entire bone. Successful repair is dependent on fracture pattern, bone quality, physician skill set, and patient tolerance of a foreign body. Plates and screws may not properly address the alignment and stability requirements for periarticular and intrarticular fractures.
Intramedullary rods or nails, such as those used in mid shaft treatments, are more effective than plates and screws at minimizing soft-tissue trauma and complications. However, rods and nails often do not stabilize multi-segment fractures in many cases. The typical intramedullary rod or nail is fixed in diameter and is introduced into the medullary canal through an incision. In cases where there is a medullary plenum larger than the rod, rotational and transverse stability may be compromised. If a larger rod is used, reaming of the entire shaft length may be necessary. Such reaming may thin out existing cortical bone support. Also, predetermined threaded screw holes in the rods may limit the ways in which different fracture patterns can be reduced and stabilized.
Flexible intramedullary rod-like solutions utilize structures that can be inserted into the medullary cavity through an access site, which can then become rigid. These solutions may be easier for the user to install than rigid intramedullary rods. These structures may be reinforced with polymers or cements. Flexible intramedullary solutions, similar to rigid intramedullary rods, may have limited benefits for periarticular or intrarticular fractures. Multi-segment fractures, of either the midshaft or end-bone, require alignment and stability in a manner that generates adequate fixation in multiple directions.
Midshaft fractures and end-bone fractures are fundamentally different. The loading conditions, fracture patterns, alignment needed, and compression force to promote healing are different. Midshaft fractures have ample bone material on either side of the fracture in which anchors may be driven. End-bone fractures, especially on the articular surface may have thin cortical bone, soft cancellous bone, and minimal anchoring locations.
Midshaft fractures tend to be loaded primarily in bending and torsion. End-bone fractures tend to be loaded in complex and multi-directional stress patterns. Midshaft repair approaches, therefore, may not be appropriate for repair of end-bone fractures.
Appropriate sizing of an implant helps realignment and healing of the fracture. As a result, many different sizes of known repair products are often stored in inventories to ensure proper matching of the implant device to a patient's anatomy. The inventories may be a burden to hospitals and insurance carriers, but they may be necessary to provide to a surgeon intraoperative flexibility.
It would be desirable, therefore, to provide apparatus and methods for proper anatomic alignment and stabilization, while reducing trauma and complications.